What is a Dry Well?

Dry wells, also known as underground injection control (UIC) systems, are stormwater infiltration devices typically constructed of a pipe approximately 3 feet wide and 20 to 50 feet deep, containing perforation at various locations along the pipe and/or at the bottom. Dry wells can be used in a variety of situations, but are especially useful in areas with clay soils to help facilitate the movement of stormwater runoff below the constricting clay layers. They are a stormwater best management practices (BMPs) to infiltrate water into the ground to reduce runoff; are relatively easy to construct; and require little land area. Dry wells can be used in conjunction with low impact development (LID) practices to help infiltrate and retain, filter, or slowly release stormwater at a given site(s). Numerous designs have been used; some includes pretreatment features such as vegetated swales and sedimentation basins that help trap sediment and other pollutants. These features will help to minimize clogging in the dry well as well as reducing contaminates released into the subsurface.

Dry wells can also provide additional benefits such as reducing the adverse effects of hydromodification on surface water quality and aquatic habitat, localized flood reduction and groundwater recharge; and can also help to adapt to the effects of drought and climate change.